Golf balls containing cis-to-trans converted polybutadiene and methods for making same

Abstract

A golf ball having at least a core and a cover, wherein at least a portion of the ball is formed from a material resulting from the isomerization of an amount of polybutadiene in solution to create a resulting polybutadiene having an increased content of trans-polybutadiene, is disclosed. Isomerization can be accomplished by mixing a photo-sensitizer into the polybutadiene solution and exposing the resulting mixture to a radiation source such as ultraviolet radiation. Isomerization can also be accomplished thermally by mixing nitrogen dioxide into a sufficiently heated solution of polybutadiene and maintaining the mixture at an elevated temperature for a sufficient period of time to increase the trans-polybutadiene content of the polymer. The resulting polybutadiene is recovered, mixed with other additives as desired and formed into one or more portions of a golf ball.

Description

TECHNICAL AREA [0001] The present invention relates to cis-to-trans, solution-converted polybutadiene for use in golf balls. BACKGROUND [0002] A variety of golf balls designed to provide a wide range of playing characteristics, i.e., the compression, velocity, “feel,” and spin, that can be optimized for various playing ability, are known in the prior art. Conventional golf balls include solid golf balls having one or more layers. Configurations of solid golf balls include one-piece balls, two-piece balls and multilayer golf balls. One-piece balls are generally easy to manufacture and relatively inexpensive. However, one-piece balls have poor playing characteristics and are typically limited for use as range balls. Two-piece balls are constructed with a solid core and a cover surrounding the core. The durability and driving distance associated with two-piece balls makes them very popular with recreational golfers. Balls having a two-piece construction are commonly formed of a polymer...

AI Technical Summary

Benefits of technology

[0012] The solution-converted butadiene rubber in accordance with the present invention reduces or eliminates the need for additional trans conversion during core curing. It also gives one the ability to de-couple the cure gradient from the trans gradient of a core, providing for example, higher trans content than could be achieved via in situ trans conversion in the relatively soft center of a core, where it can achieve the highest benefit. Other trans conversion agents (such as DTDS and zinc pentachlorothiophenol) can be omitted from the core formula, as well as the other processes associated with in situ trans conversion, such as tailoring the peroxide package and level, to the catalyst type and level.

Problems solved by technology

However, one-piece balls have poor playing characteristics and are typically limited for use as range balls.

Although two-piece balls are generally easy to manufacture and popular with recreational golfers, two-piece balls have limited playing characteristics.

Often, a softer feel is desired; however, soft feel golf balls constructed with a high cis concentration polybutadiene have low resilience.

Cis-to-trans conversion during cure, however, results in a trans gradient that roughly mirrors the cure gradient, because the two chemical reactions occur simultaneously, making it difficult to alter or reverse the trans gradient.

The direct polymerization method, however, can result in reduced molecular weight and high polydispersity, among others.

However, due to the incompatibility of these two polymers, crystallinity, which is believed to be bad for golf ball properties, is not completely eliminated.

For example, polymers that have a high percentage of the trans-polybutadiene conformation, such as DIENE 35NF, from Firestone Corp., that has 40 percent cis-isomer and 50 percent trans-polybutadiene isomer, and mixtures of high-cis and high-trans-polybutadiene isomers, such as CARIFLEX BR1220, from Shell Corporation, and FUREN 88, from Asahi Chemical Co., respectively, typically do not yield high resilience values and therefore are not desirable.

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